The invention is based on an air brake system as defined hereinafter. An air brake system of this kind has been set forth in U.S. Pat. No. 4,903,576.
In such air brake systems, the problem exists that particularly in the brake pressure increase phase before the onset of regulation by the anti-skid apparatus, severe differences in synchronization between the control pressure and the brake pressure arise. If the anti-skid apparatus begins to operate during overly forceful braking, "pressure maintenance" in the control pressure chamber of the relay valve is entirely unable to effect any "pressure maintenance" in the brake pressure chamber of the relay valve. As a result, the brake pressure in a pressure maintenance phase rises further, so that at the onset of operation of the anti-skid apparatus, very pronounced intrusions upon vehicle wheel speed often occur. At the very least, this puts the motor vehicle at risk during cornering, i.e., when the greatest lateral traction is required.
A similar effect arises in the brake pressure reduction phase, if the pressure in the control chamber of the relay valve is lowered via the magnetic valves; this pressure reduction then ensues more rapidly than the pressure reduction in the brake line.